[dpdk-stable] [PATCH v2] bus/pci: fix wrong intr_handle.type with uio_pci_generic
Yang, Zhiyong
zhiyong.yang at intel.com
Wed Jan 3 04:29:42 CET 2018
> -----Original Message-----
> From: Thomas Monjalon [mailto:thomas at monjalon.net]
> Sent: Friday, December 29, 2017 7:07 PM
> To: Yang, Zhiyong <zhiyong.yang at intel.com>
> Cc: dev at dpdk.org; Yigit, Ferruh <ferruh.yigit at intel.com>; stable at dpdk.org
> Subject: Re: [PATCH v2] bus/pci: fix wrong intr_handle.type with uio_pci_generic
>
> 29/12/2017 08:55, Zhiyong Yang:
> > For virtio legacy device, testpmd startup fails when using
> > uio_pci_generic. The issue is caused by invoking the function
> > pci_ioport_map. The right intr_handle.type is already set before
> > calling it, we should avoid overwriting the default value "RTE_
> > INTR_HANDLE_UNKNOWN" in it. Besides, the removal has no harm to other
> > cases since it already is set to this value (0) at init.
>
> To be more precise, it is set to 0 by a memset on the whole struct during
> allocation in the scan function (pci_scan_one).
>
> > --- a/drivers/bus/pci/linux/pci.c
> > +++ b/drivers/bus/pci/linux/pci.c
> > @@ -723,7 +723,6 @@ pci_ioport_map(struct rte_pci_device *dev, int bar
> __rte_unused,
> > if (!found)
> > return -1;
> >
> > - dev->intr_handle.type = RTE_INTR_HANDLE_UNKNOWN;
>
> There is the same assignment in pci_vfio_map_resource_primary(),
> pci_vfio_map_resource_secondary() and pci_uio_map_resource().
>
> Please could you check why there is such assignments?
In general, the operation in the three functions intends to initialize the "intr_handle.type",
For example,
For pci_uio_map_resource(), it wants to get "unknown" status once the code returns abnormally after initializing.
If the code goes smoothly, dev->intr_handle.type must be assigned to "RTE_INTR_HANDLE_UIO" for bsd environment,
Or must be assigned to "RTE_INTR_HANDLE_UIO" or " RTE_INTR_HANDLE_UIO_INTX" for linux environment
In consideration of the "memset" in pci_scan_one, it can be removed to has no harm to the existing logic.
Of course, keeping it is ok.
pci_vfio_map_resource_primary() and pci_vfio_map_resource_secondary() are similar.
The author was emphasizing that intr_handle.type should be initialized (0) and can be assigned to a right value after it.
Once fails, we can read a status "unknown". I guess.
Turn back to the patch, it is crude to assign "unknown" directly since pci_ioport_map is not only used by real "unknown"
But also is used to handle uio_pci_generic driver on X86 platform. It is a special case to cause error for uio_pci_generic.
Thanks
Zhiyong
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